The duration of the units is not strictly defined and may vary according to the implementation, roughly in the range of 10 milliseconds up to 1 second.
[1] Concatenative synthesis for music started to develop in the 2000s in particular through the work of Schwarz[2] and Pachet[3] (so-called musaicing).
[1][2][4] Zero Point, the first full-length album by Rob Clouth (Mesh 2020), features self-made concatenative synthesis software called the 'Reconstructor' which "chops sampled sounds into tiny pieces and rearranges them to replicate a target sound.
"[5] Clouth's concatenative synthesis algorithm was adapted from 'Let It Bee — Towards NMF-Inspired Audio Mosaicing' by Jonathan Driedger, Thomas Prätzlich, and Meinard Müller.
The new algorithm serves as the engine behind the Concatenator plugin by DataMind Audio, which is currently still in beta[10].